In the field of filtration and heat exchange, there is a device commonly used to develop separate regions; commonly referred to as a tube sheet. The tube sheet is meant to be supported in a housing or tank and is used primarily for the support of a plurality of filter elements that are usually in the form of filter tubes for filtration or heat exchange. By way of example refer to U.S. Pat. Nos. 3,715,033; 4,609,462 and 5,128,038 which describe various filter constructions in which the filter tubes are supported by the tube sheet essentially forming a boundary region by which filtration or even heat exchange can be affected. The tube sheet provides a support for the tubes, but also functions as a bulkhead to the media on either side of the tube sheet; effectively maintaining a discontinuity so that transformation can take place.
In actual operation, there are times when differential pressures on opposing sides of the tube sheet are in excess of normal operating differential pressures; substantial pressures in and of themselves. In order to overcome the differential pressure and maintain structural rigidity the tube sheet is typically produced of a substantial thickness, and machined to a high tolerance to accept the tubes. One particular disclosure of a tube sheet is shown in the '462 patent as tube sheet 32.
This tube sheet thickness solves the problem of structural rigidity while simultaneously serving the purpose of a bulkhead and a means to maintain the spacing between the tubes. This comes at a cost. The machining process which typically is by drilling or water jet cutting is a slow and costly process to produce the sufficiently rigid, high tolerance barrier required.
In a typical tube sheet construction the tube sheet may be formed of a metal material such as stainless steel and can have a thickness on the order of ½ inch. A sheet of stainless steel is fabricated to various diameters; between less than one foot in diameter up to a diameter of greater than 5 feet in diameter, and then holes [one to 2500 or more holes] are drilled with a conventional drill bit or water jet cutter to facilitate insertion of the tube elements. This process is cumbersome and very time consuming; as much as 20 hours or more to produce one sheet 5 feet in diameter.
The vast majority of tube sheets in use are fabricated in this fashion, whether it is for use in a heat exchanger, filter, for reverse osmosis, distillation, or as a condenser, evaporator, or for fuel cell applications. An objective of the present invention is to provide a multi-segment tube sheet wherein, instead of drilling a one-piece thick plate, the tube sheet is formed in multiple segments which are then fastened together to provide structural rigidity.
Another objective of the present invention is to provide an improved tube sheet which eliminates the costly and time consuming steps to manufacture as with present day tube sheets.
Still another objective of the present invention is to provide an improved tube sheet structure including a stacked assembly of thinner sheets, that when assembled together provide the structural integrity of the present day tube sheet but at a substantially manufacturing reduced cost.
A further objective of the present invention is to provide an improved tube sheet structure including a stacked assembly of thinner sheets, and in which the thinner sheets are more readily processed for creating holes therein such as by being punched on an automated press, burned with a laser or a plasma cutter, or formed by being printed using additive manufacturing technologies; ie 3D printing as but one example.
Another objective of the present invention is to provide an improved tube sheet construction including an interstitial layer referred to herein as a media layer so that the tube sheet functions both as a tube sheet as well as a multifunctional processing device.
A further objective of the present invention is to provide an improved tube sheet construction that provides, in addition to multiple sheet segments, a unique intermediate layer referred to herein as a media layer for providing any one of a number of additional functions including, but not limited to, filtration, flow control, shock absorption, magnetic characteristics, dosing, chemical or medical treatment, or ion exchange.